I know that putting them in a kennel while you are gone works, but that has always seemed a bit too confining for an active puppy to me-I put up that toddler-proof fencing in an area of the utility room and put my puppy, her food, water, bed and toys in there when I was gone, and that worked just fine.
That's pretty much what I did with my first dog when I worked. With this one I'm at home so I was able to let him outside constantly. I never could bring myself to do the cage thing.